BRATTLEBORO — A large fire engulfed a seven-unit apartment building on Elliot Street in downtown Brattleboro, leaving about 20 people homeless Wednesday night.

No one was believed to have been hurt, and all residents were safely evacuated, according to early reports.

Residents of the four-story grey clapboard apartment building said the fire started on the top floor of the back porch and spread to the rest of the building. The porch overlooked Frost Place.

Tenants of the building showed videos taken on their smartphones, showing the top floor of the porch engulfed in flames and spreading to the lower levels.

Shaquran Holcomb and his girlfriend Jody Beaman live on the ground floor apartment, and Holcomb took pictures of the back porch in flames.

Holcomb and Beaman said they had lived in the building for two years, and that it was a good place to live.

Beaman said she was at work in Putney at the time the fire broke out and she rushed home.

Holcomb said six of the seven apartments were occupied at the time. The couple conferred with other tenants and watched as fire crews fought the blaze, which in the early stages was extremely smoky.

The fire, which broke out before 6 p.m., had sent giant clouds of smoke into the air, visible from Interstate 91. Several ladder trucks from local fire departments were called to help fight the fire, including one from Keene, N.H.

Most of the tenants of the building, which is owned by Bob Remy-Powers of Brattleboro, gathered at a command center set up on the west end of Elliot Street, staffed by Acting Town Manager Patrick Moreland and members of the Red Cross.

A Red Cross spokeswoman said a shelter would be set up for the residents of the building, and if necessary, they would be placed in area motels.